Laboratory Analysis
First-line peripheral blood laboratory evaluation should include
complete blood count with differential, complete metabolic panel
including total protein, albumin, and liver functions, lactate
dehydrogenase (LDH), lipid panel, and, in the case of chylous ascites,
lipase. Depending on the severity of lymphatic leak, secondary
laboratory evaluations may include PT/ aPTT/ INR and fibrinogen to
monitor for the ongoing development of coagulopathy and an
immunoglobulin panel (IgA, IgG, IgM) to monitor for the ongoing
development of hypogammaglobulinemia.
Aspiration of fluid via thoracentesis or paracentesis is critical to
establish a diagnosis of lymphatic leak. Simple observation of the
aspirated fluid can start to differentiate the fluid as exudative (e.g.
lymphatic) versus transudative (from heart failure, hepatic cirrhosis,
nephrotic syndrome) in origin.[16] If the child has been enterally
fed, chyle will appear cloudy, milky white although it can also appear
serous, sanguineous or bloody. Evaluation of the pleural or peritoneal
fluid that supports lymphatic origin include elevated concentration of
protein, LDH, triglyceride, increased presence of lymphocytes, and the
presence of chylomicrons (Table 2) . If three is concern for
PLE, stool can be evaluated for alpha-1-antitrypson.
Biopsies of abnormal lymphatic tissue may help with histologic diagnosis
of disease, but caution should be taken in the setting of lymphatic leak
not to risk exacerbating the condition. Biopsy of involved rib bones can
be particularly dangerous as this may exacerbate lymphatic leak. In
conjunction with clinical history, physical examination, imaging and
fluid analysis, if biopsy is felt to be helpful, biopsy of affected
tissue remote from an active leak is recommended.